The present invention relates to an apparatus for detecting a failure in bearings, and particularly to an apparatus which uses acoustic emission (hereinafter referred to as AE).
Devices such as the following have conventionally been used as bearing failure detection apparatuses for detecting bearing failure by detecting acoustic emission. This bearing failure detection apparatus detects AE signals from bearings using an AE sensor, compares the output of the AE sensor in a comparator with a threshold value, and judges a bearing abnormality when the AE signal exceeds the aforementioned threshold value. Furthermore, the number of events in which the AE signal level exceeds a given threshold level is counted, and a bearing failure is judged by whether the sum of these events exceeds a given threshold value.
However, because the aforementioned conventional bearing failure detection apparatus judges bearing failure by simply determining whether the AE signal level exceeds a given threshold level, there has been a problem of erroneous bearing failure detection in factories in which are installed rolling mills which produce strong AE signals at the metal-in time (i.e. - the time when the rolling of a metal sheet is started or the time when the metal sheet is loaded into the mill) and at other times because strong AE signals from sources other than the bearings cannot be discriminated from the AE signal from the bearing themselves.